1. Field of the Invention
The present invention relates to an improved process for preparing hydroxyalkylphenyl ether and thioether compounds. In particular, the present invention is directed to an improved process for preparing hydroxyalkylphenyl ether and thioether compounds by reacting a phenolic compound or a thiophenolic compound with a cyclic organic carbonate. The improvement comprises reacting the phenolic or thiophenolic compound and cyclic organic carbonate in the presence of a triorganophosphine catalyst.
2. Prior Art
Hydroxyalkylphenyl ethers and thioether compounds are well known and well reported in the literature. Some of these compounds are used commercially. For example, resorcinol di-(2-hydroxyethyl) ether, also known as hydroxyethyl resorcinol, is an intermediate for the manufacture of polyurethane elastomers and for the manufacture of polyesters. Bisphenol-A-di-(-2-hydroxyethyl) ether is a useful diol for preparing corrosion resistant polyesters and bisphenol-A-di-(-2 hydroxypropyl) ether is a useful diol for making binder resins for glass fibers. The O-hydroxyalkylation of phenol/formaldehyde and phenol/resorcinol/formaldehyde resins also yields useful compounds.
There are two well known processes for preparing hydroxyalkylphenyl ethers and thioethers. One process comprises reacting the phenolic compound or thiophenolic compound with an organic oxide such as ethylene oxide, propylene oxide, styrene oxide and the like. While this process has been used commercially, it has several drawbacks. First of all it is necessary to use special buried tanks and pressure equipment to handle the ethylene oxide or propylene oxide. In addition, special precautions are necessary to minimize the formation of poly-oxyalkylated products. In addition, its usually necessary to purify the hydroxyalkylated products before they can be used in further reactions.
The other well known method for preparing O-hydroxyalkylated phenols and thiophenols is the reaction of the phenolic or thiophenolic compounds with cyclic organic carbonates. Carlson U.S. Pat. No. 2,448,767 discloses the reaction of phenols and thiophenols with ethylene carbonate. According to Carlson, the reaction can be carried out in the presence or absence of a suitable solvent and in the presence or absence of a suitable catalyst. Catalysts that were disclosed by Carlson as being useful were acids such as concentrated sulfuric acid, bases such as alkali carbonates and alkali salts of phenol. The preferred catalysts of Carlson were alkali carbonates or alkali salts of phenol. T. Yoshimo et al. in J. Chem. Soc. Japan, 46(2), 555(1973) discloses the use of lithium hydroxide or tetraalkylammonium halides as catalysts for this reaction.
In addition, Dow Chemical Company has the following seven patents assigned to it that cover various materials as catalysts for the reaction of phenolic compounds or thiophenolic compounds with cyclic organic carbonates. Smith U.S. Pat. No. 3,967,892 discloses alkali metal hydroxides as the catalyst. Davis U.S. Pat. No. 2,987,555 discloses alkali metal hydrides as the catalyst. Kem U.S. Pat. No. 4,261,922 teaches the use of potassium iodide. Strege U.S. Pat. No. 4,310,706 covers an imidazole as the catalyst and Strege U.S. Pat. No. 4,310,707 covers sodium stannate as the catalyst. Strege et al. U.S. Pat. No. 4,310,708 teaches the use of quaternary phosphonium salts such as triphenylbutylphosphonium bicarbonate as the catalyst. Finally, Strege U.S. Pat. No. 4,341,905 discloses alkali metal halides such as potassium fluoride as the catalyst.
Although many of these catalyst systems are effective, they generally suffer from one or more of the following drawbacks. Many of these catalysts are ionic salts and have to be neutralized and/or removed before the hydroxyalkylated phenols can be used. Ionic salt catalysts have corrosion producing potential. In addition, the ionic salts have a deleterious effect on the oxidative stability of end products made with the hydroxyalkylated phenols. In addition, if all the ionic species are not removed, end products made with the hydroxyalkylated phenols will have poor electrical properties and may be discolored. While all of the catalysts mentioned above are effective, they do not give essentially quantitative yields of product. Some of the catalysts are also difficult to handle and are quite expensive.